Microfluidic devices, with their ability to manipulate and analyze nanoliter volumes of chemicals and other fluids, have attracted great interest across a broad range of research and industrial applications. Corporate and academic laboratories around the world are deeply engaged in developing manufacturing technologies for these devices, hoping to create the same kind of benefits and value that accrued from the miniaturization and large scale integration of electronic devices. The flexibility and programmability of direct laser ablation make it attractive as a fabrication technology, but many other aspects of its performance remain to be understood and characterized. Advanced confocal microscopy, which provides fast, high-resolution, threedimensional visualization and measurement of micrometer scale structure, is ideally suited to this characterization task.